i haven't changed my oil since i bought my car a while ago so i think i'd better give it a service. Just wondering what the best type to use is ie. synthetic, semi synthetic or a good quality non synthetic? cheers

How many miles have put on the car since you bought it? Thats a scary.

How many miles are on the car? For higher mileage cars I'd recommend a semi- to full synthetic, 10W-30 is the average. If its cold maybe a 5w-30 or maybe even 5w-20.

only about 400miles. its done about 90,000 miles so iguess semi would be best then?

walmart supertech oil is just fine for our cars

Mobil 1 10w-30 is the best. I did a lot of research at one point to figure that out. I didn't save any of it, but if you do a search I'm confident that you will come to the same conclusion. It's the best for the money. Racing oils are better, but cost significantly more.

i use Castrol 10W-30 and it works perfect

personally... oil is oil. All the same stuff. The only kicker is synthetics... but for the most part... mineral oil is mineral oil. The thing is... keep it changed and clean... and within specs. I usually run 10W40

synthetic is good if ur driving more highway....regualr castrol, pennzoil, etc.. is good for normal stop n go driving....and depending on your mileage...the more miles u have the more wear n tera u have in yoru motor....on a new motor a thinner oil like 5w-20/30 works best....and the more miles u pack in yoru motor the higher u go....i refer my customers below 75k miles 5w-20/30....75k+ miles 10w-30 and 10w-40 during the winter......170k+ miles 20w-50.....

got that info from where i work at - ADVANCE

i might be wrong..but its jus a selling point in my shoes....idk bout u guys

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cars switching to synthetic at higher mileage is more likely for a leak to pop up.

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false, its just a myth. i switched to syn at 115k and my leaky valve seals went away after i switched.

if you get a leak after switching to syn you were going to get a leak anyways, wether you switched or not.

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You got any proof its a myth? I have been told this by some VERY reputable people and believe it to be the case.

its a myth thats been passed down from person to person for soo long that its hard to break the cycle.

its just about IMPOSSIBLE to find reliable and truthful information about oil on the internet due to extreme amounts of advertising put into pages and reviews by mobil and amsoil and other companies.

if i could find a true unbiased non advertising article i would link it, but ive heard from many people that are REALLY in the know (dealer techs with 30+ years working in the automotive feild and ASE certified master techs) that switching to synthetic doesnt increase your chances of an oil leak anymore than the reason the sky is blue is because of all the water

an old engine will leak oil no matter what you do, it just happens and its such a hard thing to scientifically study. just because mr x has an oil burning issue at 180k miles and he switched to synthetic and now it blows blue smoke doesnt mean its because of the oil, it could be countless other things. hell it could be because the synthetic cleaned away the varnish and sludge that was holding the engine together :lol:

I use Castrol Formula R 5w/30 in my car.
I'm happy with it

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You laugh at this but the cleaning effects of synthetic and its ability to break down sludge that has plugged spots where oil would leak is PRECISELY the reason I understand why people sometimes develop a leak after switching to synthetic on a high milage engine.

guys its not a myth.

i don't want to get into a argument so lets just leave it as
its not a myth....

think about it. its simple the atoms of the synthetic oil moves at a velocity that is subject to heat.
so if you multiply the mass of the nucleus of the atom by the gravitational pull of the moon divided that by 57 take newton's First Law witch states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.

My car:
230,000+ miles. Used dino (non-synthetic) oil all her life. She runs fine - no leaks.

~J~

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if the engine was that BADLY plugged with sludge and varnish then it is probably already on its last legs and could start leaking/burning at any minute.

it is a myth! i switched and my leaky valve seals went away! i was using penzoil before and on startup after the car sat for 8 hours or more i would puff out some oil. now after i switched to synthetic it got worse for about a month and then went away. hell its not even the OIL itself thats what matters here, its the additive package. mobil one isnt a synthetic base oil anyways, its a PAO base oil. its organic and made from some type of seed if i remember correctly. its the ADDITIVES that are sythetic in it, those synthetic additives last longer and that pao base oil is more temprature resistant and has a more uniform flow rate. it may still be organic but its more refined than an engine oil made from petroleum.

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This is also exactly why you need to switch you oil at about 500 and then 1000 then 1500, after switching. That slug it breaks loose can plug up your system and cause you to have no oil. This is very important. Synthetic oil lubricates a lot better than regular oils, and it cleans. Anything that cleans and breaks up slug will undoubtedly have the ability to assist in the engine leaking. I would rather have a car leak on synthetic than not leak on regular. At least you know it's clean.

btw, it's Castrol that has an organic base. But it still works like a synthetic, and pretty much is one. I've never heard that Mobil one is like that, but if it is, I don't think that really matters. It's all about how it preforms.

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I agree with the bulldog. You got any proof Bitter? Hook me up with a link.

look on the front of mobil and you'll see a little * then look on the back and it says something about a non synthetic base oil.


the BEST way to clean the innards of your engine is with some ATF every other oil change. add about 1/2 qt 100 miles before the oil change.

Hey Bitter, would you be convinced that switching to synthetic can cause your engine to leak oil if I found an article written by an Amsoil representative that said just that?

Why synthetic oil can cause leaks

So much for your myth theory....

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and its clear you didnt read the whole propaganda article, you just skimmed the top.

This post has been edited by Bitter: Mar 21, 2006 - 1:33 PM

I read the whole article. Surely you are not going to maintain your myth theory after reading that? Just so you know, its ok to be wrong. It happens to me all the time. When I am wrong, I just admit it and go on. No big deal!

Fortunately, oil manufacturers learned their lesson and reformulated their oil to contain the proper additive package which helps condition seals and gaskets to maintain their flexibility while also maintaining proper seal swell. In fact, the reformulation in most cases provides for better seal conditioning than most petroleum oils these days. Nevertheless, there is still a possibility of leakage if making the switch to synthetic - but only under certain conditions. Please allow me to elaborate a little bit.

Any of you who are considering a switch to synthetic oils probably know by now that petroleum oils do not necessarily keep your engine squeaky clean. Well, if you own an older vehicle (over 8-10 years old) it's possible that you have leaks in your engine already. Now, before you string me up by my toe nails telling me there's never been a drop of oil that leaked from your engine, let me explain myself.

On older vehicles which have been lubricated with petroleum oils, seals and gaskets can begin to dry and crack. The reason you don't actually see leaks is because petroleum oils tend to burn off and leave sludge, grime and varnish on the inside of your engine. That's simply the nature of a petroleum oil's make-up. Now, conventional petroleum oils are not very discriminatory about where they leave those deposits. Therefore, some of the deposits end up around your seals and gaskets which actually plugs up the gaps which would have resulted in oil leaks.

Not even close. The fact is, it's a result of using petroleum oil instead of a high quality synthetic that resulted in dry and cracking seals & gaskets in the first place. As I mentioned earlier, synthetic oils now contain special additives which maintain proper seal swell and keep them flexible so that seals and gaskets don't dry and crack in the first place. So, for those people who use synthetic oils from the start (after a 3,000 to 5,000 mile break-in period), the problem never becomes an issue.


so i guess you didn't read that part of the propaganda realy close? it says you engine is leaking but you just dont see it.

and i still dispute the validity of this article since it was written FOR Amsoil by someone who sells Amsoil.

If you are going to quote the article, it is best to quote the relevant portion. Fortunately, its the part that came right after the part you copied. Since you might not have seen it, I will post it here for you:

Of course, the next obvious question is, "If synthetics have those special additives, why might they cause leaks in an older engine? Why don't they correct the problem?"

Believe it or not, I've got an answer for that too. The "problem" is that there are also other additives that give a synthetic oil its detergency properties. In other words, there's other stuff in high quality synthetic oil which tends to clean out the sludge and deposits left behind by petroleum oils. Once these deposits are gone, the gaps around seals and gaskets become exposed and the oil might begin to leak in these areas.

As for your argument that this was written by an Amsoil dealer so that means the information is suspect, lets think about that. Amsoil makes synthetic oil. Therefore, if they are going to "spin" the article, they are surely going to do it in favor of synthetics. Here they admit that switching might cause oil leaks. Why would that admission be biased?

I switched to mobil1 at about 75000 and have noticed consumtion.
Don't know where its going can't find leaks but its going somewhere.

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Maybe they are trying the old reverse psychology thing. I never really thought it was debatable if synthetics could help the leaks leak. They don't cause them themselves necessarily, but they will open up holes that were plugged by petroleum oils. All that needs to be proven is that synthetics have a detergent or cleaning additive in them that can break up slug left by other oils. If that can be proved, there is no contest here.

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give it some time or try sucking some ATF through a manifold vac line into the engine and then letting it sit over night. ATF has awesome additives that are GREAT for rubber seals in engines and transmissions as well as very strong detergents that will help to clean the intake manifold and combustion chambers somewhat.

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What is ATF? I wish people would type things like that out sometimes. Those abriviations aren't universally understood.